This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Objective: To evaluate the role of the lateral prefrontal cortex in modulating emotion and in mediating the behavioral and physiological characteristics of the anxious endophenotype. We defined three groups of rhesus monkeys exhibiting low, medium, and high levels of freezing behavior (behavioral inhibition) which is associated with the anxious endophenotype. We further characterized these animals on other behavioral and physiological measures and used microPET and MRI to examine brain activity and structure. These measures are being used to evaluate specific contributions of brain regions to emotion processing. This research used WNPRC Animal Services, surgery, operational services, and library and information services.